For your custom module if you want to join your custom table data with Magento default product collection then you need to join tables with the entiry_id of the product and your product_id stored in your custom table. Here I have just used the resource model collection to join the table. I tried with getmodel feature of Magento don’t know why it doesn’t able to create the Product grid in the backend. So I used resource model and it worked. If you are only joining the table, not to generate the Product grid, then you can use getmodel instead of resource model.

    $collection = Mage::getResourceModel(‘catalog/product_collection’)
                    ->addAttributeToSelect(‘name’)
                    ->addAttributeToSelect(‘sku’)
                    ->addAttributeToSelect(‘price’)
                    ->addAttributeToSelect(‘status’)
                    ->addAttributeToSelect(‘visibility’)
                    ->addAttributeToFilter(‘type_id’, array(‘eq’ => ‘simple’))
                    ->addFieldToFilter(‘status’, Mage_Catalog_Model_Product_Status::STATUS_ENABLED)
                    ->addAttributeToFilter(‘visibility’, array(‘neq’ => 1));
    
    $collection->getSelect()->join(array(‘mep’ => “mage_brand_product”), “e.entity_id = mep.product_id”, array(‘mep.*’));